GPS POI和观点

Question

Thanks to Cosines or Haversine formulas, I get a list of POIs ordered by there distance from where I am.

How can I get to the next level and select the POIs that correspond to the direction I'm looking at (let's say 15°+/-5°, 0=North, 90=East)?

There is not much code already. We could use an exemple like this

$gps_pos = array (
                 'lat'=>48.845364, 
                 'lng'=>2.406628, 
                 'distance'=>20);
$pois = GetPOIsFromGPS($gps_pos);

There $pois looks like

Array
(
    [0] => Array
        (
            [id] => 336047
            [gps_lat] => 48.84528500
            [gps_lng] => 2.40663900
            [gps_alt] => 0.0000
            [distance_in_kms] => 0.0088094293255129
        )
    [1] => Array
        (
            [id] => 955092
            [gps_lat] => 48.84520700
            [gps_lng] => 2.40657700
            [gps_alt] => 0.0000
            [distance_in_kms] => 0.017828309444397
        )

    [2] => Array
        (
            [id] => 1022839
            [gps_lat] => 48.84515700
            [gps_lng] => 2.40644600
            [gps_alt] => 0.0000
            [distance_in_kms] => 0.026556875382492
        )
)

The trick is now to make de GetPOIsInPOV function.

$pov = array ('hdegres' => 15, 'range'=>5);

$pois_in_pov = GetPOIsInPOV($pois, $pov);

Thanks